Methods and apparatus for reference signal design for interference cancellation

Abstract

Methods and apparatus for reference signal design are provided. In some aspects, a base station determines one or more of: a demodulation reference signal (DMRS) sequence or a DMRS location pattern, based on at least one of a plurality of transmission characteristics, and transmits one or more of the determined DMRS sequence or the determined DMRS location pattern. In further aspects, a user equipment identifies one or more of: a demodulation reference signal (DMRS) sequence or a DMRS location pattern from a base station, determines at least one of a plurality of transmission characteristics of the first base station based on one or more of: the identified DMRS sequence or the identified DMRS location pattern, and performs interference cancellation for transmissions from the base station.

What is claimed is: 
     
       1. A method of wireless communication, comprising:
 determining, by a base station based on at least one transmission characteristic of the base station of a plurality of transmission characteristics of the base station, one or more of a demodulation reference signal (DMRS) sequence including at least one DMRS symbol or a DMRS location pattern including a set of resource elements; and 
 transmitting, by the base station, a DMRS using at least one of the one or more of the DMRS sequence or the DMRS location pattern. 
 
     
     
       2. The method of  claim 1 , wherein the plurality of transmission characteristics of the base station include one or more of:
 a transmission mode, wherein the transmission mode includes at least a space frequency block coding (SFBC) mode and a non-SFBC mode; 
 a transmission waveform; 
 a transmission content; or 
 mini-slot partitioning structure used during transmission. 
 
     
     
       3. The method of  claim 1 , wherein the determining the DMRS sequence includes determining different DMRS sequences for different DMRSs indicating different transmission characteristics of the base station, wherein the different DMRS sequences are orthogonal to each other and located in a same set of resource elements. 
     
     
       4. The method of  claim 1 , wherein the one or more of the DMRS sequence or DMRS location pattern are determined to minimize cross-correlation within a transmission block by a user equipment (UE) receiving a transmission of the one or more of the DMRS sequence or the DMRS location pattern. 
     
     
       5. The method of  claim 1 , wherein the determining the DMRS sequence includes determining different DMRS sequences for different resource blocks or resource block groups. 
     
     
       6. The method of  claim 5 , wherein the determining the different DMRS sequences includes scaling the at least one symbol in the DMRS sequence by a phase, wherein the phase is associated with a resource block or a resource block group. 
     
     
       7. The method of  claim 5 , wherein the determining the different DMRS sequences includes providing different DMRS sequences so that a same DMRS sequence is not used in multiple of one or more of resource blocks (RBs), resource block groups (RBGs), or precoding resource block groups (PRGs) to avoid an increase of peak-to-average power ratio (PAPR). 
     
     
       8. The method of  claim 1 , wherein the determining the DMRS location pattern includes determining different DMRS location patterns for different DMRSs indicating different transmission characteristics, wherein the different DMRS location patterns do not overlap each other. 
     
     
       9. The method of  claim 1 , further comprising transmitting one or more transmission parameters to another base station, wherein the one or more transmission parameters include one or more of:
 a slot type; 
 a resource block group size; 
 a number of control symbols; 
 structure of mini-slot partitioning; 
 subcarrier spacing; 
 a cell identification (ID); or 
 a virtual cell ID. 
 
     
     
       10. The method of  claim 9 , further comprising transmitting the one or more transmission parameters in a coordinated multi-point operation. 
     
     
       11. A method of wireless communication, comprising:
 identifying, by a user equipment (UE), one or more of a demodulation reference signal (DMRS) sequence or a DMRS location pattern in a transmission from a first base station; 
 determining, by the UE, at least one transmission characteristic of the first base station of a plurality of transmission characteristics of the first base station based on the one or more of the DMRS sequence or the DMRS location pattern; and 
 performing, by the UE, interference cancellation for transmissions from the first base station. 
 
     
     
       12. The method of  claim 11 , further comprising receiving one or more transmission parameters of the first base station from a second base station or the first base station, wherein the one or more transmission parameters include one or more of:
 a slot type; 
 a resource block group size; 
 a number of control symbols; 
 structure of mini-slot partitioning; 
 subcarrier spacing; 
 a cell identification (ID); or 
 a virtual cell ID. 
 
     
     
       13. The method of  claim 12 , further comprising receiving the one or more transmission parameters from the first base station in a coordinated multi-point operation. 
     
     
       14. The method of  claim 12 , further comprising informing the second base station of transmission information desired for the interference cancellation from the first base station, wherein the transmission information includes one or more of: the one or more transmission parameters, or an indication of interference cancellation capabilities of the UE. 
     
     
       15. The method of  claim 14 , wherein the informing the second base station of the transmission information includes signaling the transmission information to the second base station dynamically or semi-statically. 
     
     
       16. An apparatus configured for wireless communication, the apparatus comprising:
 at least one processor; and 
 a memory coupled to the at least one processor, wherein the at least one processor is configured:
 to determine, by a base station based on at least one transmission characteristic of the base station of a plurality of transmission characteristics of the base station, one or more of a demodulation reference signal (DMRS) sequence including at least one DMRS symbol or a DMRS location pattern including a set of resource elements; and 
 to transmit, by the base station, a DMRS using at least one of the one or more of the DMRS sequence or the DMRS location pattern. 
 
 
     
     
       17. The apparatus of  claim 16 , wherein the plurality of transmission characteristics include one or more of:
 a transmission mode, wherein the transmission mode includes at least a space frequency block coding (SFBC) mode and a non-SFBC mode; 
 a transmission waveform; 
 a transmission content; or 
 mini-slot partitioning structure used during transmission. 
 
     
     
       18. The apparatus of  claim 16 , wherein the configuration of the at least one processor to determine the DMRS sequence includes configuration to determine different DMRS sequences for different DMRSs indicating different transmission characteristics of the base station, wherein the different DMRS sequences are orthogonal to each other and located in a same set of resource elements. 
     
     
       19. The apparatus of  claim 16 , wherein the configuration of the at least one processor to determine one or more of the DMRS sequence or the DMRS location pattern are determined to minimize cross-correlation within a transmission block by a user equipment (UE) receiving a transmission of the one or more of the DMRS sequence or the DMRS location pattern. 
     
     
       20. The apparatus of  claim 16 , wherein the configuration of the at least one processor to determine the DMRS sequence includes configuration to determine different DMRS sequences for different resource blocks or resource block groups. 
     
     
       21. The apparatus of  claim 20 , wherein the configuration of the at least one processor to determine the different DMRS sequences includes configuration to scale the at least one symbol in the DMRS sequence by a phase, wherein the phase is associated with a resource block or a resource block group. 
     
     
       22. The apparatus of  claim 20 , wherein the configuration of the at least one processor to determine the different DMRS sequences includes providing different DMRS sequences so that a same DMRS sequence is not used in multiple of one or more of resource blocks (RBs), resource block groups (RBGs), or precoding resource block groups (PRGs) to avoid an increase of peak-to-average power ratio (PAPR). 
     
     
       23. The apparatus of  claim 16 , wherein the configuration of the at least one processor to determine the DMRS location pattern includes configuration to determine different DMRS location patterns for different DMRSs indicating different transmission characteristics, wherein the different DMRS location patterns do not overlap each other. 
     
     
       24. The apparatus of  claim 16 , wherein the at least one processor is further configured to transmit one or more transmission parameters to another base station, wherein the one or more transmission parameters include one or more of:
 a slot type; 
 a resource block group size; 
 a number of control symbols; 
 structure of mini-slot partitioning; 
 subcarrier spacing; 
 a cell identification (ID); or 
 a virtual cell ID. 
 
     
     
       25. The apparatus of  claim 24 , wherein the at least one processor is further configured to transmit the one or more transmission parameters in a coordinated multi-point operation. 
     
     
       26. An apparatus configured for wireless communication, the apparatus comprising:
 at least one processor; and 
 a memory coupled to the at least one processor, wherein the at least one processor is configured:
 to identify, by a user equipment (UE), one or more of a demodulation reference signal (DMRS) sequence or a DMRS location pattern in a transmission from a first base station; 
 to determine, by the UE, at least one transmission characteristic of the first base station of a plurality of transmission characteristics of the first base station based on the one or more of the DMRS sequence or the DMRS location pattern; and 
 to perform, by the UE, interference cancellation for transmissions from the first base station. 
 
 
     
     
       27. The apparatus of  claim 26 , wherein the at least one processor is further configured to receive one or more transmission parameters of the first base station from a second base station or the first base station, wherein the one or more transmission parameters include one or more of:
 a slot type; 
 a resource block group size; 
 a number of control symbols; 
 structure of mini-slot partitioning; 
 subcarrier spacing; 
 a cell identification (ID); or 
 a virtual cell ID. 
 
     
     
       28. The apparatus of  claim 27 , wherein the at least one processor is further configured to receive the one or more transmission parameters from the first base station in a coordinated multi-point operation. 
     
     
       29. The apparatus of  claim 27 , wherein the at least one processor is further configured to inform the second base station of transmission information desired for the interference cancellation from the first base station, wherein the transmission information includes one or more of: the one or more transmission parameters, or an indication of interference cancellation capabilities of the UE. 
     
     
       30. The apparatus of  claim 29 , wherein the configuration of the at least one processor to inform the second base station of the transmission information includes configuration to signal the transmission information to the second base station dynamically or semi-statically.